Semiconductor device structure with anti-acid layer and method for forming the same

ABSTRACT

A semiconductor device structure and method for forming the same are provided. The semiconductor device structure includes an interconnect structure formed over a substrate and a passivation layer formed over the interconnect structure. The semiconductor device structure also includes an anti-acid layer formed in the passivation layer and a bonding layer formed on the anti-acid layer and the passivation layer. The anti-acid layer has a thickness that is greater than about 140 nm.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon. Many integrated circuits are typically manufactured on a single semiconductor wafer, and individual dies on the wafer are singulated by sawing between the integrated circuits along a scribe line. The individual dies are typically packaged separately, in multi-chip modules, for example, or in other types of packaging.

An image sensor is used to convert an optical image focused on the image sensor into an electrical signal. The image sensor includes an array of light-detecting elements, such as photodiodes, and a light-detecting element is configured to produce an electrical signal corresponding to the intensity of light impinging on the light-detecting element. The electrical signal is used to display a corresponding image on a monitor or provide information about the optical image.

Although existing image sensor device structures and methods for forming the same have been generally adequate for their intended purpose, they have not been entirely satisfactory in all aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It should be noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIGS. 1A-1F show cross-sectional representations of various stages of forming a complementary metal-oxide-semiconductor (CMOS) image sensor structure, in accordance with some embodiments of the disclosure.

FIGS. 2A-2E show perspective representations of various stages of forming a complementary metal-oxide-semiconductor (CMOS) image sensor structure, in accordance with some embodiments of the disclosure.

FIGS. 3A-3D show cross-sectional representations of various stages of forming a complementary metal-oxide-semiconductor (CMOS) image sensor structure, in accordance with some embodiments of the disclosure.

FIGS. 4A-4E show cross-sectional representations of various stages of forming a semiconductor device structure, in accordance with some embodiments of the disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the subject matter provided. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements. It should be understood that additional operations can be provided before, during, and after the method, and some of the operations described can be replaced or eliminated for other embodiments of the method.

Embodiments for a semiconductor device structure and method for forming the same are provided. FIGS. 1A-1F show cross-sectional representations of various stages of forming a complementary metal-oxide-semiconductor (CMOS) image sensor structure 300 a, in accordance with some embodiments of the disclosure. The structure 300 a is a backside illuminated (BSI) image sensor structure. FIGS. 2A-2E show perspective representations of various stages of forming a complementary metal-oxide-semiconductor (CMOS) image sensor structure 300 a, in accordance with some embodiments of the disclosure.

Referring to FIG. 1A, a semiconductor device structure 100 a includes a substrate 102. In some embodiments, the substrate 102 is a portion of a wafer. The substrate 102 has a frontside 102 a and a backside 102 b.

The substrate 102 may be made of silicon or other semiconductor materials. Alternatively or additionally, the substrate 102 may include other elementary semiconductor materials such as germanium. In some embodiments, the substrate 102 is made of a compound semiconductor such as silicon carbide, gallium arsenic, indium arsenide, or indium phosphide. In some embodiments, the substrate 102 is made of an alloy semiconductor such as silicon germanium, silicon germanium carbide, gallium arsenic phosphide, or gallium indium phosphide. In some embodiments, the substrate 102 includes an epitaxial layer. For example, the substrate 102 has an epitaxial layer overlying a bulk semiconductor.

The substrate 102 may further include isolation features 108, such as shallow trench isolation (STI) features or local oxidation of silicon (LOCOS) features. Isolation features may define and isolate various device elements.

The substrate 102 may further include doped regions (not shown). The doped regions may be doped with p-type dopants, such as boron or BF₂, and/or n-type dopants, such as phosphorus (P) or arsenic (As). The doped regions may be formed directly on the substrate 102, in a P-well structure, in an N-well structure, or in a dual-well structure.

A transistor including a gate dielectric layer 112 and a gate electrode layer 114 is formed at the frontside 102 a of the substrate 102. The spacers 116 are formed on opposite sidewalls of the gate electrode layer 114. The source/drain (S/D) structures 118 are formed in the substrate 102.

Other device elements include transistors (e.g., metal oxide semiconductor field effect transistors (MOSFET), complementary metal oxide semiconductor (CMOS) transistors, bipolar junction transistors (BJT), high-voltage transistors, high-frequency transistors, p-channel and/or n channel field effect transistors (PFETs/NFETs), etc.), diodes, and/or other applicable elements may formed over the substrate 102. Various processes are performed to form device elements, such as deposition, etching, implantation, photolithography, annealing, and/or other applicable processes. In some embodiments, device elements are formed in the substrate 102 in a front-end-of-line (FEOL) process.

Afterwards, an inter-layer dielectric (ILD) layer 110 is formed over the frontside 102 a of the substrate 102, as shown in FIG. 1A, in accordance with some embodiments of the disclosure. The ILD layer 110 may include multilayers. The ILD layer 110 is made of silicon oxide (SiOx), silicon nitride (SixNy), silicon oxynitride (SiON) or low-k dielectric material, another applicable dielectric material.

A contact structure 120 is formed in the ILD layer 110 and over the S/D structure 118. The contact structure 120 is made of conductive material, such as such as copper (Cu), copper alloy, aluminum (Al), aluminum alloy, tungsten (W), tungsten alloy, titanium (Ti), titanium alloy, tantalum (Ta), tantalum alloy, or another applicable materials.

An interconnect structure 130 is formed over the ILD layer 110. The interconnect structure 130 includes an inter-metal dielectric (IMD) layer 132, a conductive via plug 134, and a conductive line 136. The IMD layer 132 may be a single layer or multiple layers. The conductive via plug 134 and the conductive line 136 are formed in the IMD layer 132. The conductive line 136 is electrically connected to another adjacent conductive line 136 through the conductive via plug 134. The interconnect structure 130 is formed in a back-end-of-line (BEOL) process.

The IMD layer 132 is made of silicon oxide (SiOx), silicon nitride (SixNy), silicon oxynitride (SiON), dielectric material(s) with low dielectric constant (low-k), or combinations thereof. In some embodiments, the IMD layer 132 is made of an extreme low-k (ELK) dielectric material with a dielectric constant (k) less than about 2.5. In some embodiments, ELK dielectric materials include carbon doped silicon oxide, amorphous fluorinated carbon, parylene, bis-benzocyclobutenes (BCB), polytetrafluoroethylene (PTFE) (Teflon), or silicon oxycarbide polymers (SiOC). In some embodiments, ELK dielectric materials include a porous version of an existing dielectric material, such as hydrogen silsesquioxane (HSQ), porous methyl silsesquioxane (MSQ), porous polyarylether (PAE), porous SiLK, or porous silicon oxide (SiO₂). In some embodiments, the IMD layer 132 is deposited by a plasma enhanced chemical vapor deposition (PECVD) process or by a spin coating process.

The conductive via plug 134 and the conductive line 136 are independently made of copper (Cu), copper alloy, aluminum (Al), aluminum alloy, tungsten (W), tungsten alloy, titanium (Ti), titanium alloy, tantalum (Ta) or tantalum alloy. In some embodiments, the conductive via plug 134 and the conductive line 136 are formed by a plating method.

As shown in FIG. 1A, a top surface of the conductive line 136 is level with a top surface of the IMD layer 132. In other words, the conductive line 136 and the IMD layer 132 are coplanar. The metal routings of the conductive features shown in FIG. 1A, are merely examples. Alternatively, other designs of metal routings of conductive features may be used according to actual application.

FIG. 2A shows a perspective representation of the interconnect structure 130 over the substrate 102, in accordance with some embodiments of the disclosure. The interconnect structure 130 is formed over the frontside 102 a of the substrate 102.

After forming the interconnect structure 130, an anti-acid layer 146 is formed over the top surface of the conductive line 136 and a top surface of the IMD layer 132, as shown in FIG. 1B, in accordance with some embodiments of the disclosure. The anti-acid layer 146 is configured to provide good acid resistance to prevent the acid solution diffusing into the underlying layers. The acid solution may be used in the subsequent process. In some embodiments, the acid solution is used to clean surfaces or removed undesirable contamination.

In some embodiments, the substrate 102 is a portion of a wafer, and the top surface of the wafer is completely covered by the anti-acid layer 146. The top surface of the interconnect structure 130 is completely covered by the anti-acid layer 146. More specifically, no passivation layer is formed between the top surface of the interconnect structure 130 and a bottom surface of the anti-acid layer 146. The anti-acid layer 146 includes a metal nitride layer 142 and a metal layer 144. The metal nitride layer 142 is in direct contact with the top surface of the interconnect structure 130. The metal nitride layer 142 includes a metal element that is the same as that of the metal layer 144. In some embodiments, the metal nitride layer 142 is tantalum nitride (TaN), and the metal layer 144 is tantalum (Ta). In some embodiments, the tantalum (Ta) is β phase tantalum (Ta). The β phase tantalum (Ta) have higher corrosion resistance than a phase. In some other embodiments, the metal nitride layer 142 is titanium nitride (TiN), and the metal layer 144 is titanium (Ti).

In some embodiments, the metal nitride layer 142 is made of a physical vapor deposition (PVD) process. In some embodiments, the PVD process is performed by using nitrogen (N₂) and argon (Ar) gas. In some embodiments, the nitrogen gas has a flow rate in a range from about 20 sccm to about 100 sccm. In some embodiments, a ratio of the flow rate of the nitrogen gas to the flow rate of the argon (Ar) gas is in a range from about 0.2 to 1. If the flow rate of the nitrogen gas is smaller than 20 sccm or the ratio smaller than 0.2, the diffusion barrier properties may be poor. If the flow rate of the nitrogen gas is larger than 100 sccm or the ratio larger than 1, formation of the metal nitride layer may become difficult.

In some embodiments, the metal nitride layer 142 has a first thickness T₁ in a range from about 5 nm to about 10 nm. In some embodiments, the metal nitride layer 142 has a second thickness T₂ in a range from about 135 nm to about 240 nm. The thickness T_(t) of the anti-acid layer 146 is the sum of the first thickness T₁ and the second thickness T₂. In some embodiments, the thickness T_(t) of the anti-acid layer 146 is in a range from about 140 nm to about 250 nm. If the thickness T_(t) is smaller than 140 nm, the anti-acid ability or acid resistant properties may be poor, and therefore the underlying layers may be etched. If the thickness T_(t) of the anti-acid layer 146 is greater than 250 nm, the risk of the contamination may increase because the deposition time is too long. Furthermore, the fabricating time and cost are increased.

Furthermore, the anti-acid layer 146 is configured to be used as a diffusion barrier layer. The diffusion barrier layer is used to prevent the bonding layer 150, which will be formed later, from migrating to underlying layers.

It should be noted that, in some other embodiments, if a diffusion barrier layer below a conductive structure has a thickness smaller than 140 nm, the thickness may be enough to form a barrier against the migration of the conductive material, but it is too thin to prevent the underlying layers from being etched by the acid solution. The acid solution may easily penetrate through the thin diffusion barrier layer. Therefore, in order to have good acid-resistant properties, the anti-acid layer 146 including metal nitride layer 142 and the metal layer 144 with a thickness T_(t) larger than 140 nm is provided.

FIG. 2B shows a perspective representation of the anti-acid layer 146 over the substrate 102, in accordance with some embodiments of the disclosure. More specifically, the metal layer 144 covers all top surface of the substrate 102.

After forming the anti-acid layer 146, the bonding layer 150 is formed over the anti-acid layer 146, as shown in FIG. 1C, in accordance with some embodiments of the disclosure. The bonding layer 150 is configured to electrically connect to other layers.

The bonding layer 150 is made of conductive material. In some embodiments, the bonding layer 150 is made of aluminum copper (AlCu) alloy, and the aluminum copper alloy containing 95% to 99.5% aluminum and 0.5% to 5% copper. In some other embodiments, the bonding layer 150 is made of aluminum (Al), titanium (Ti), tantalum (Ta), copper (Cu), tungsten (W), alloy thereof. In some embodiments, the bonding layer 150 is formed by a deposition process, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), plating, another applicable process or the like. In some embodiments, the bonding layer 150 has a thickness in a range from about 1200 nm to about 1500 nm. In some embodiments, a ratio of the anti-acid layer 146 to the bonding layer 150 is in a range from about 4 to about 11. When the ratio is within the above-mentioned range, the anti-acid property is improved.

It should be noted that after the bonding layer 150 is formed, a quality test is performed on the semiconductor device structure 100 a. In some embodiments, the quality test includes a bonding ability test and anti-acid test. After forming the bonding layer 150, the bonding ability test is performed to check if the bonding layer can resist a high force. After the bonding ability test, the bonding layer 150 will be removed to continue the following anti-acid test. The anti-acid layer 146 is exposed to an acid solution. The anti-acid test is used to test if the conductive via plug 134 and the conductive line 136 will be etched by the acid solution or not. In some embodiments, the acid solution is aqua regia (also called “king's water”) which is formed by mixing concentrated nitric acid (HNO₃) and hydrochloric acid (HCl), in a volume ratio of 1:3.

If the thickness of the anti-acid layer 146 is not thick enough, the acid solution may pass or penetrate through the anti-acid layer 146 and etch a portion of the conductive via plug 134 and the conductive line 136. By forming the anti-acid layer 146 with a greater thickness Tt than 140 nm, the semiconductor device structure 100 a passes the anti-acid test. Therefore, the anti-acid layer 146 protects the underlying layers from being etched. In addition, the reliability of the semiconductor device structure 100 a is further increased.

It should be noted that normal quality test does not include the anti-acid test, it may be not needed to control the thickness of the anti-acid layer. However, in some embodiments, the anti-acid test is needed to ensure the quality of the anti-acid layer 146. Therefore, in order to pass the anti-acid test, the thickness of the anti-acid layer 146 of the disclosure should be well controlled to equal to or greater than 140 nm. If the thickness of the anti-acid layer 146 is smaller than 140 nm, the underlying layer may be etched and delaminated easily.

It should be noted that the anti-acid layer 146 and the bonding layer 150 are sequentially performed at the same CMP station. In other words, the deposition processes are performed in-situ without being transported to another station for convenience and efficiency.

A protecting layer 152 is formed over the bonding layer 150 to temporarily protect the bonding layer 150 during transferring the semiconductor device structure 100 a. When the protecting layer 152 is formed, the semiconductor device structure 100 a is removed from the chamber and ready for bonding. The protecting layer 152 is made of inert metal material. In some embodiments, the protecting layer 152 is made of tantalum (Ta), titanium (Ti), iron (Fe), copper (Cu) or a combination thereof.

Before bonding process, the protecting layer 152 is replaced by a passivation layer 154. In some embodiments, the passivation layer 154 is made of non-organic materials, such as silicon oxide, un-doped silicate glass, silicon oxynitride, solder resist (SR), silicon nitride, HMDS (hexamethyldisilazane). In some other embodiments, the passivation layer 154 is made of a polymer material, such as polyimide (PI), epoxy, or fluorine (F)-containing polymer.

Afterwards, a planarizing process is performed on the backside 102 of the substrate 102 to thin the backside 102 b of the substrate 102, as shown in FIG. 1C, in accordance with some embodiments of the disclosure. In some embodiments, the planarizing process is a chemical mechanical polishing (CMP) process. The planarizing process is configured to decrease the height of the semiconductor device structure 100 a.

FIG. 2C shows a perspective representation of the protecting layer 152 over the frontside 102 a of the substrate 102, in accordance with some embodiments of the disclosure. More specifically, the protecting layer 152 is formed over the bonding layer 150. The top surface of the bonding layer 150 is completely covered by the protecting layer 152.

After the palarizing process, the substrate 102 has a fourth thickness T₄ (shown in FIG. 1D) which is smaller than the third thickness T₃ (shown in FIG. 1C).

Afterwards, an image sensor device structure 200 a is prepared, as shown in FIG. 1D, in accordance with some embodiments of the disclosure. The image sensor device structure 200 a includes a substrate 202. A number of pixel regions 210 are formed in the substrate 202. In some embodiments, the image sensor device structure 200 a is free from, or substantially free from, logic devices (such as logic transistors).

The pixel regions 210 may include pixels 210R, 210G and 210B corresponding to specific wavelengths. For example, the pixels 210R, 210G and 210B respectively correspond to a range of wavelengths of red light, green light and blue light. Therefore, each of the pixels 210R, 210G and 210B may detect the intensity (brightness) of a respective range of wavelengths. The term “pixel” refers to a unit cell containing features (for example, circuitry including a photodetector and various semiconductor devices) for converting electromagnetic radiation into electrical signals. In some embodiments, the pixels 210R, 210G, and 210B are photodetectors, such as photodiodes including light-sensing regions. The light-sensing regions may be doped regions having n-type and/or p-type dopants formed in device substrate 102. The light-sensing regions may be formed by an ion implantation process, diffusion process, or other applicable processes.

FIG. 2D shows a perspective representation of the semiconductor device structure 100 a and the image sensor device structure 200 a before performing a bonding process, in accordance with some embodiments of the disclosure. The backside 102 b of the substrate 102 faces the top surface of the substrate 202 before the bonding process.

Afterwards, the semiconductor device structure 100 a and the image sensor device structure 200 a are bonded together to form a 3DIC stacking structure 300 a, as shown in FIG. 1E, in accordance with some embodiments of the disclosure. In some embodiments, the substrate 102 and the substrate 202 both are made of silicon, and a bonding process for bonding of the substrate 102 and the substrate 202 is performed under pressure and heat.

Afterwards, in some embodiments, a number of openings (not shown) are formed in the passivation layer 154, and the conductive bump structure 156 is formed in the openings. The conductive bump structure 156 is electrically connected to the bonding layer 150.

FIG. 2E shows a perspective representation of the semiconductor device structure 100 a and the image sensor device structure 200 a after the bonding process, in accordance with some embodiments of the disclosure. The 3DIC stacking structure 300 a includes the semiconductor device structure 100 a and the image sensor device structure 200 a. The pixels 210R, 210G, and 210B are formed below the backside 102 b of the substrate 102.

Afterwards, a doped layer 212 is formed over the exposed pixels 210R, 210G and 210B as shown in FIG. 1F, in accordance with some embodiments of the disclosure. In some embodiments, the doped layer 212 is formed directly on the pixels 210R, 210G and 210B. The doped layer 212 is formed over the backside 102 b of the substrate 102. The doped layer 212 is configured to improve the image quality of the image sensor. In some embodiments, the doped layer 212 is doped with p-type dopants, such as boron or BF₂, and/or n-type dopants, such as phosphorus (P) or arsenic (As).

Afterwards, an antireflection layer 214 is formed over the doped layer 212. The antireflection layer 214 is made of dielectric materials, such as silicon nitride, silicon oxynitride, or anther applicable material.

Next, a color filter layer 216 is formed over the antireflection layer 214. The incident light may be filtered by the color filter layer 216 and the filtered incident light, such as being transformed into red light, may reach the pixels 210R, 210G and 210B. In some embodiments, the color filter layer 216 is made of a dye-based (or pigment-based) polymer for filtering out a specific frequency band. In some embodiments, the color filter layer 216 is made of a resin or other organic-based materials having color pigments.

Afterwards, a microlens layer 218 is formed over the color filter layer 216. Each of the microlenses is aligned with one of the corresponding color filter layers 216, and therefore is aligned with one of the corresponding pixels 210R, 210G and 210B. However, it should be noted that microlenses may be arranged in various positions in various applications.

Therefore, the CMOS image sensor structure 300 a is obtained. The anti-acid layer 146 is formed over the backside 102 b of the substrate 102. In other words, the anti-acid layer 146 is formed above the pixels 210R, 210G and 210B. The anti-acid layer 146 with a thickness that is greater than 140 nm has good acid resistant properties.

FIGS. 3A-3D show cross-sectional representations of various stages of forming a complementary metal-oxide-semiconductor (CMOS) image sensor structure 300 b, in accordance with some embodiments of the disclosure. The structure 300 b is a frontside illuminated (BSI) image sensor structure.

The semiconductor device structure 100 b shown in FIG. 3A is similar to, or the same as, the semiconductor device structure 100 a shown in FIG. 1C, except a conductive structure 156 is formed in the passivation layer 154. The top surface of the conductive structure 156 is level with the top surface of the passivation layer 154.

Afterwards, an image sensor device structure 200 b is prepared, as shown in FIG. 3B, in accordance with some embodiments of the disclosure. The image sensor device structure 200 b includes pixels 210R, 210G and 210B formed in the substrate 202. The substrate 202 includes a frontside 202 a and a backside 202 b. An interconnect structure 204 formed over the frontside 202 a of the substrate 202. The interconnect structure 204 includes an inter-metal dielectric (IMD) layer 205, a conductive line 206 and a conductive via plug 208. The conductive line 206 and the conductive via plug 208 are formed in the IMD layer 205.

Afterwards, the semiconductor device structure 100 b and the image sensor device structure 200 b are bonded together by hybrid bonding to form a 3DIC stacking structure 300 b, as shown in FIG. 3C, in accordance with some embodiments of the disclosure.

The hybrid bonding involves at least two types of bonding, including metal-to-metal bonding and non-metal-to-non-metal bonding. As shown in FIG. 3C, a hybrid bonding structure 305 is formed between the semiconductor device structure 100 b and the image sensor device structure 200 b. The hybrid bonding structure 305 includes the conductive bump structure 156 and the conductive line 206 bonded by metal-to-metal bonding and the passivation layer 154 and the IMD layer 205 bonded by non-metal-to-non-metal bonding. In some embodiments, the hybrid bonding may be performed in an inert environment, such as an environment filled with inert gas including N₂, Ar, He, or combinations thereof.

As shown in FIG. 3C, the bonding structure 305 has a metallic bonding interface 305 a between the conductive bump structure 156 and the conductive line 206 but may not have a clear non-metallic interface between the passivation layer 154 and the IMD layer 205 due to the reflow process.

Afterwards, a doped layer 212 is formed over the exposed pixels 210R, 210G and 210B as shown in FIG. 3D, in accordance with some embodiments of the disclosure. The doped layer 212 is formed over the backside 202 b of the substrate 202. The doped layer 212 is configured to improve the image quality of the image sensor.

Afterwards, the antireflection layer 214 is formed over the doped layer 212. Next, the color filter layer 216 is formed over the antireflection layer 214. The incident light may be filtered by the color filter layer 216 and the filtered incident light, such as being transformed into red light, may reach the pixels 210R, 210G and 210B.

Afterwards, the microlens layer 218 is formed over the color filter layer 216. The microlens layer 218 is aligned with one of the corresponding color filter layers 216, and therefore is aligned with one of the corresponding pixels 210R, 210G and 210B.

Therefore, the CMOS image sensor structure 300 b is obtained. The anti-acid layer 146 is formed over the frontside 102 a of the substrate 102. In other words, the anti-acid layer 146 is formed below the pixels 210R, 210G and 210B. The anti-acid layer 146 with a thickness that is greater than 140 nm has good acid resistant properties. Therefore, the reliability of the CMOS image sensor structure 300 b is improved.

FIGS. 4A-4E show cross-sectional representations of various stages of forming a semiconductor device structure 100 c, in accordance with some embodiments of the disclosure. The semiconductor device structure 100 c is similar to, or the same as, the semiconductor device structure 100 a shown in FIG. 1A, except a passivation layer 160 is formed over the interconnect structure 130. Processes and materials used to form a semiconductor device structure 100 c may be similar to, or the same as, those used to form the semiconductor device structure 100 a and are not repeated herein.

As shown in FIG. 4A, the passivation layer 160 is formed over the interconnect structure 130, and openings 162 are formed in the passivation layer 160. The openings 162 are formed by a patterning process.

After forming the openings 162, a metal nitride layer 142 and a metal layer 144 are sequentially formed in the openings 162 and over the passivation layer 160, as shown in FIG. 4B, in accordance with some embodiments of the disclosure.

The metal nitride layer 142 is conformally formed on the bottom and sidewall of the openings 162. The metal nitride layer 142 and the metal layer 144 are collectively named as an anti-acid layer 146. The anti-acid layer 146 is used to prevent the underlying layer from being corroded in the subsequent process.

The metal nitride layer 142 includes a metal element that is the same as that of the metal layer 144. In some embodiments, the metal nitride layer 142 is tantalum nitride (TaN), and the metal layer 144 is tantalum (Ta). In some other embodiments, the metal nitride layer 142 is titanium nitride (TiN), and the metal layer 144 is titanium (Ti).

After forming the metal layer 144, the bonding layer 150 is formed in the openings 162 and on the metal layer 144, as shown in FIG. 4C, in accordance with some embodiments of the disclosure. In some embodiments, the bonding layer 150 is made of AlCu alloy.

Afterwards, the metal nitride layer 142, the metal layer 144 and the bonding layer 150 are patterned, as shown in FIG. 4D, in accordance with some embodiments of the disclosure.

Afterwards, the conductive bump structure 156 is formed on the bonding layer 150. The conductive bump structure 156 is electrically connected to the bonding layer 150, as shown in FIG. 4E, in accordance with some embodiments of the disclosure.

It should be noted that anti-acid layer 146 and the bonding layer 150 are sequentially provided at the same CMP station. In other words, the deposition processes are performed in-situ without being transported to another station for convenience and efficiency.

It should be noted that in order to protect the underlying layers from being etched or removed, the thickness of the anti-acid layer 146 of the disclosure should be well controlled to equal to or greater than 140 nm. If the thickness of the anti-acid layer 146 is smaller than 140 nm, the underlying layer may be etched and delaminated easily.

Embodiments for forming a semiconductor device structure and method for formation the same are provided. A semiconductor device structure includes a substrate, and an interconnect structure formed over the substrate. An anti-acid layer formed over the interconnect structure. A bonding layer formed over the anti-acid layer and a number of pixel regions formed over a backside of the substrate or over the bonding layer. The anti-acid layer is configured to protect the underlying layers from being damaged by the acid solution which may be used in the subsequent process. In some embodiments, the anti-acid layer is formed in a passivation layer. In some embodiments, the anti-acid layer has a thickness that is greater than about 140 nm to effectively block the etching of the acid. Therefore, the reliability of the semiconductor device structure is improved.

In some embodiments, a complementary metal-oxide-semiconductor (CMOS) image sensor structure is provided. The CMOS image sensor structure includes a substrate having a frontside and a backside and an interconnect structure formed over the frontside of the substrate. The CMOS image sensor structure also includes an anti-acid layer formed over the interconnect structure and a bonding layer formed over the anti-acid layer. The CMOS image sensor structure further includes a number of pixel regions formed over the backside of the substrate or over the bonding layer.

In some embodiments, a semiconductor device structure is provided. The semiconductor device structure includes an interconnect structure formed over a substrate and a passivation layer formed over the interconnect structure. The semiconductor device structure also includes an anti-acid layer formed in the passivation layer and a bonding layer formed on the anti-acid layer and the passivation layer. The anti-acid layer has a thickness that is greater than about 140 nm.

In some embodiments, a method for forming a complementary metal-oxide-semiconductor (CMOS) image sensor structure is provided. The method includes providing a substrate having a frontside and a backside and forming an interconnect structure over the frontside of the substrate. The method also includes forming an anti-acid layer over the interconnect structure and forming a bonding layer over the anti-acid layer. The method further includes forming a plurality of pixels over the backside of the substrate or over the bonding layer.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

1. A complementary metal-oxide-semiconductor (CMOS) image sensor structure, comprising: a substrate having a frontside and a backside; an interconnect structure formed over the frontside of the substrate; an anti-acid layer formed over the interconnect structure; a bonding layer formed over the anti-acid layer; a plurality of pixel regions including a first photodetector corresponding to red light, a second photodetector corresponding to blue light and a third photodetector corresponding to green light formed over the backside of the substrate or over the bonding layer; and a first microlens aligned with the first photodetector, a second microlens aligned with the second photodetector and interposing the first microlens and a third microlens, and the third microlens aligned with the third photodetector, wherein the first, second and third microlens are disposed on an opposite side of the respective first, second and third photodetector than the substrate, wherein the anti-acid layer contiguously extends over the substrate from above or below the first microlens to above or below the third microlens.
 2. The CMOS image sensor structure as claimed in claim 1, wherein the anti-acid layer comprises a metal nitride layer and a metal layer, and the metal nitride layer comprises a metal element that is the same as that of the metal layer, and wherein each of the metal layer and the metal nitride layer contiguously extend from above or below the first microlens to above or below the third microlens.
 3. The CMOS image sensor structure as claimed in claim 1, wherein the anti-acid layer has a thickness in a range from about 140 nm to about 250 nm.
 4. The CMOS image sensor structure as claimed in claim 2, wherein the metal nitride layer is tantalum nitride (TaN), and the metal layer is tantalum (Ta).
 5. The CMOS image sensor structure as claimed in claim 4, wherein the tantalum (Ta) is βphase tantalum (Ta).
 6. The CMOS image sensor structure as claimed in claim 2, wherein the metal nitride layer is titanium nitride (TiN), and the metal layer is titanium (Ti).
 7. The CMOS image sensor structure as claimed in claim 1, further comprising: a passivation layer formed over the bonding layer; a first conductive bump structure formed in the passivation layer, wherein the conductive bump structure is electrically connected to the bonding layer; and a second conductive bump structure formed in the passivation layer, wherein the anti-acid layer contiguously extends from under the first conductive bump structure to under the second conductive bump structure.
 8. The CMOS image sensor structure as claimed in claim 1, further comprising: a color filter layer of dye-based polymer over each of the plurality of pixel regions.
 9. A semiconductor device structure, comprising: an interconnect structure formed over a substrate, wherein the interconnect structure includes a top surface comprising a top inter-metal dielectric (IMD) layer and a top conductive line; an anti-acid layer disposed over the top IMD layer and the top conductive layer; and a bonding layer formed on the anti-acid layer and the passivation layer, wherein the anti-acid layer has a thickness that is greater than about 140 nm; a first conductive bump structure formed over the bonding layer and a second conductive bump structure formed over the bonding layer, wherein the anti-acid layer having the thickness extends from below the first conductive bump structure to below the second conductive bump structure.
 10. The semiconductor device structure as claimed in claim 9, wherein the anti-acid layer is in direct contact with the planar top surface including directly contacting the top IMD layer and the top conductive layer of the interconnect structure.
 11. The semiconductor device structure as claimed in claim 9, wherein the anti-acid layer has a thickness in a range from about 140 nm to about 250 nm.
 12. The semiconductor device structure as claimed in claim 9, wherein the anti-acid layer comprises a metal nitride layer and a metal layer, and the metal nitride layer comprises a metal element which is the same as that of the metal layer.
 13. The semiconductor device structure as claimed in claim 12, wherein the metal nitride layer is tantalum nitride (TaN), and the metal layer is tantalum (Ta).
 14. The semiconductor device structure as claimed in claim 13, wherein the tantalum (Ta) is βphase tantalum (Ta).
 15. The semiconductor device structure as claimed in claim 9, wherein the first conductive bump structure is electrically connected to the bonding layer. 16.-20. (canceled)
 21. A complementary metal-oxide-semiconductor (CMOS) image sensor structure, comprising: a gate electrode layer formed over a first substrate; an interconnect structure formed on the gate electrode layer; an anti-acid layer formed on the interconnect structure, wherein the anti-acid layer completely covers a top surface of the interconnect structure; a bonding layer formed on the anti-acid layer, wherein the bonding layer is made of conductive material; a second substrate formed below the first substrate; and a plurality of pixel regions each comprising a photodiode formed in the second substrate.
 22. The CMOS image sensor structure as claimed in claim 21, wherein the anti-acid layer comprises a metal nitride layer and the metal layer, and the metal nitride layer comprises a metal element that is the same as that of the metal layer.
 23. The CMOS image sensor structure as claimed in claim 21, further comprising: a color filter layer over the plurality of pixel regions; and a plurality of microlens over the color filter layer, wherein each respective pixel of the plurality of pixel regions has a single microlens disposed under the respective pixel.
 24. The CMOS image sensor structure as claimed in claim 21, further comprising: a passivation layer formed over the bonding layer; and a conductive bump structure formed in the passivation layer, wherein the conductive bump structure is electrically connected to the bonding layer.
 25. The CMOS image sensor structure as claimed in claim 21, wherein the metal nitride layer is tantalum nitride (TaN), the metal layer is tantalum (Ta), and the tantalum (Ta) is β phase tantalum (Ta). 